558 



THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1951 

 15.0 



10.0 

 9.0 

 8.0 

 7.0 



6.0 



in 5.0 



!: 



o 



> 4.0 



z 



3.0 

 2.5 



2.0 

 1.5 



3 4 5 6 7 8 9 10 15 20 25 30 



Cc IN MICRO-MICROFARADS 



Fig. 25 — Collector capacitance decreases as collector voltage is increased. 



^A^ — r 



a. 



■AM/ — (3^ 



Fig. 26 — The equivalent circuit of a transistor with collector capacitance shown. 



re 





Fig. 27 — The effect of collector capacitance is to change r,« and Tc to Vm and r'c See 



equations (67) and (68). 



Figure 25 shows measured values of Ce as a function of collector voltage. 

 For rfasons which are not understood at present, these data show a de- 

 parture from the usual inverse one- third power variation. At Vc = 4.5 volts 



